Achieving High Luminescent Performance K2SiF6:Mn4+ Phosphor by Co-precipitation Process with Controlling the Reaction Temperature

K2SiF6:Mn4+ (KSF:Mn) phosphor was synthesized by the one-step co-precipitation process, at different temperatures. It was found that the reaction temperature played a key role in photoluminescence performance of the product. When the reaction temperature decreased from 0°C to − 20°C, the doping concentration, Mn/Si ratio, increased from 2% to 10%. However, further decrement of temperature (to − 30°C) reduced the Mn/Si ratio to 7%. The photo-luminescence (PL) intensity was maximized at the highest Mn/Si (10%), which corresponds to a reaction temperature of − 20°C. The KSF:Mn phosphor showed excellent luminescent properties at a wide range of temperatures (from room temperature to 470 K), especially after being dispersed in a polymer matrix. When combined with a commercial white light emitting diode (WLED), KSF:Mn significantly improved luminescent properties, such as color rendering index (CRI), correlated color temperature (CCT) and luminous efficiency. In particular, CRI increased from 67.3 to 87.4, while the CCT decreased from 7800 K to 3204 K. The luminous efficiency increased from 82.0 lm/W to 95.3 lm/W. The results indicated that the high quality KSF:Mn red phosphor could be achieved by a simple one-step co-precipitation method with a fine control of reaction temperature.